Household doorbells are typically connected to an AC transformer that converts high voltage AC current (e.g., 120 Volts) to low voltage AC current (e.g., 12 Volts). Some low voltage devices such as doorbell cameras may require a voltage or current that is not supported by legacy transformers in older households. For example, a user may install and connect a new doorbell camera to an existing transformer only to realize afterward that the new doorbell camera is inoperable and not supported by the existing transformer. Therefore, testing and diagnostic of the new doorbell camera after its installation forces the user to unmount and uninstall the doorbell camera, replace the transformer, and reinstall the new doorbell camera.